Chromatin exists in a large number of structural and functional states. The purpose of this project is to examine chromatin structure with a view toward the presence of nucleosomes, the packing of nucleosomes and the three dimensional organization of chromatin fibers. The following functional states will be studied using stereo transmission electron microscopy and standard biochemical methods: supranucleosomal structure in sea urchin sperm, chicken erythrocytes and stylonychia macro - and micro-nuclei; transcription in nucleoli and Balbiani rings of Chironomus salivary gland cells; replication in the macronucleus of Stylonychia; and metaphase chromosomes in CHO cells and Dictyostelium.